The present invention relates to a wear-resistant coating and component.
In production of tools, molds, and machine parts, various types of coatings have been applied to a substrate to improve properties such as hardness, wear resistance, corrosion resistance, lubricity, ductility, strength, and elasticity. Unfortunately, many of these properties are mutually exclusive for a given material. Thus one material or composition may possess good hardness but may not have lubricity or some other desirable property. For example, a coating of a boride, carbide, nitride or carbonitride of titanium, hafnium, or zirconium is very hard, but lacks lubricity or ductility, which is a desirable property for machine components. On the other hand, lubricious materials such as germanium and fluorocarbons do not possess sufficient hardness or wear resistance. Hard coating materials such as diamond-like carbon and titanium diboride are usually very brittle which limits their wear resistance. The high internal stress also prohibits depositing thick coating material which is crucial in some tribological applications such as wear reduction in hard particle erosion environment.
Multilayer coating technology is increasingly used in improving properties of tools and components because multiple layers of materials having different properties can be tailored to provide a particular combination of desirable and opposing properties such as for example, hardness, lubricity, and ductility. Suitable multilayer coatings include combinations of hard crystalline layers, such as TiC or TiN, and lubricative amorphous carbon layers. However, the amorphous carbon coating easily peels off from underlying TiC or TiN layer during or immediately after formation of the coating because of the high thermal and internal stress of the amorphous carbon layer and its poor compatibility with underlying TiC or TiN layer. Thus intermediate layers having complex compositions are required to adhere the TiC/TiN layer to the amorphous carbon layer or vice versa. These layers include graded composition layers which have a changing composition of carbon and TiC or TiN through their thickness. The graded composition layers are difficult to fabricate and often have undesirable properties of low hardness or lubricity.
Thus there is a need for a coating for a wear-resistant component that exhibits high hardness and wear resistance, as well as opposing properties of lubricity and ductility. There is a further need for a multilayer or multi-component coating that can be strongly adhered to a component. There is also a need for a method of making a wear-resistant component that efficiently and reliably coats the component with a hard and ductile coating.